Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The best time to plant calla lily in Philadelphia can be determined by referring to the USDA zone info.

Planting Calendar for Calla Lily

Frost tolerance for calla lily:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since calla lily are not cold tolerant you need to wait until after the last frost has passed before you can plant them.

The earliest that you can plant calla lily in Philadelphia is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant calla lily and expect a good harvest is probably August. If you wait any later than that and your calla lily may not have a chance to grow to maturity. Starting your calla lily indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Philadelphia. It might get as low as 0°F during the coldest months of winter.

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Philadelphia and it will vary from year to year. Half of the time in Philadelphia you get surprised by a frost after April 15 so make sure that you are ready to protect your calla lily if you have one of those late frosts.

USDA Zone Info for Philadelphia

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Philadelphia

You may be interested in your other planting guides for Philadelphia.